This makes sure we also enforce authorizations for non-nullable
fields.

We are defining our authorizations on the unwrapped
types (Repository). But when a type like that is presented in a
non-nullable field, it's type is different (Repository!). The
non-nullable type would not have the authorization metadata.

This makes sure we check the metadata on the unwrapped type for
finding authorizations.

Add the missing check on GraphQL API for project statistics

This exposes `Note`s on Issues & MergeRequests using a
`Types::Notes::NoteableType` in GraphQL.

Exposing notes on a new type can be done by implementing the
`NoteableType` interface on the type. The presented object should
be a `Noteable`.

We can query namespaces, and nested projects.

Projects now exposes statistics

With this we only check abilities on the rendered edges of a GraphQL
connection instead of all the nodes in it.

- Show pipeline status, title, MR Status and project path
- Popover attached to gitlab flavored markdown everywhere, including:
  + MR/Issue Title
  + MR/Issue description
  + MR/Issue comments
  + Rendered markdown files